1. Field
Example Embodiments relate to semiconductor devices and methods of fabricating the same, and more particularly, to semiconductor devices that may have a gate-all-around (GAA) structure and methods of fabricating the same.
2. Description of Related Art
As the integration density of semiconductor devices increases, design rules for components of the semiconductor devices may become stricter. For example, in semiconductor devices requiring a large number of transistors, gate length, which is one of the criteria of the design rules, may decrease, and thus channel length may decrease. The reduction in the channel length of transistors may lead to an increase in short channel effects.
The short channel effect may refer to the decrease of threshold voltage as the effective channel length of a transistor may decrease due to a drain potential effect. Because of this short channel effect, it may be difficult to control a transistor, and the OFF current of a transistor may increase. As a result, the reliability of transistors, for instance the refresh characteristic of a memory device, may deteriorate.
Currently, research is being conducted into a semiconductor device including a transistor that may have a fin-channel structure that may use surfaces of the fins as channels, a so-called fin type field effect transistor (finFET), which may be able to reduce or inhibit the short channel effect that exists in conventional planar type transistors and simultaneously increase operating current.
Conventional finFets may use upper and lateral surfaces of a fin as a channel region. Conventional finFets may also use lateral and upper surfaces, and part of a lower surface of a semiconductor fin as a channel region.
However, conventional finFETs may be fabricated using a silicon-on-insulator (SOI) substrate, thus having higher fabrication costs. Further, because an entire lower surface of the fin is not used as the channel region, there may be a limitation on the increase of the operating current. Hence, research has been conducted into a finFET that may have a gate-all-around (GAA) structure where the entire area, e.g. lateral, upper and lower surfaces, of the fin may be able to be used as the channel region, and various semiconductor devices using the same.